US Colt M1873 Single Action Army revolver, here a first generation in .45 Long Colt (1917).
The Peacemaker was designed for the U.S. government service revolver trials of 1872 by Colt's Patent Firearms Manufacturing Company and was adopted as the standard military service revolver until 1892.

Colt Single Action Army revolver manufactured in 1897. The revolver has a full nickel plated finish, fitted with smooth two-piece mother of pearl grips and decorated with factory scroll engraving on a punch-dot background. The engraving was executed by Hartley & Graham and is very similar to Colt "B" engraving of the same period. The top of the barrel is roll-stamped with the two-line legend: "COLT'S PT. F.A. Co./HARTFORD. CT. U.S.A.". The left side of the barrel is roll-stamped with the caliber designation, "45 COLT" in an engraved panel. The left side of the frame is roll-stamped with the Colt 'Three-Date/Two-Line' patent markings in an oval engraved panel. The assembly number, "135" is stamped on the loading gate. The serial number, "169693" is stamped on the bottom of the frame, trigger guard and back strap. The accompanying factory letter verifies the caliber, nickel finish, factory engraving, hard rubber grips at the time of shipment which was to Hartley & Graham, New York, N.Y. on March 25, 1897. The revolver is accompanied by a hand tooled, russet, saddle leather," Mexican Loop" holster and matching 43-round cartridge belt. The holster is decorated with a silver concho and hand tooled floral designs with a leather lining. The holster loops are stamped with "swastika" style marks which at this period of time were viewed as good luck symbols. The folded leather cartridge/money belt has a silver-plated buckle. http://rockislandauction.com/detail/56/229/colt-single-action-army#detail

This scarce black powder, Colt Single Action Army Revolver was manufactured in 1877. The revolver is chambered for the .44-40 W.C.F. cartridge. The left side of the trigger guard flat is marked "44.C.F." and the underside of the early block address barrel is stamped with the caliber designation "44". Although the Colt chambered Single Action Army Revolvers for the .44-40 cartridge as early as 1876, surviving examples are very scarce. John Kopec states in "COLT SINGLE ACTION ARMY REVOLVER" that the "44.C.F." stamping on the trigger guard was introduced about serial number 41,800. The revolver has a blued barrel, cylinder, trigger guard and back strap. The frame, hammer and loading gate have a casehardened finish. The one-piece, walnut, grip is varnished. The ejector rod has a 'bullseye' head. The top of the barrel is roll-stamped with the block letter Hartford address: "COLT'S PT. F A MFG. Co, HARTFORD, CT. U.S.A.". The address lacks the slashes at either end and there is no period in "Co". The left side of the frame is roll-stamped with the Colt 'three date/three line' patent marking. The inside of the loading gate is stamped with the assembly number "1723". The full serial number "40956", is located on the frame, trigger guard and back strap. The barrel and cylinder are stamped with the partial serial number "0956" and "0956" is written in ink on the grip back strap recess. All of the serial numbers match. The rear face of the cylinder is stamped with a small "P" and a "B" Colt inspection marks is stamped in the hammer well above the firing pin hole.
BBL: 7 1/2 inch round
Gauge: 44-40 WCF
Finish: blue/casehardened
Grips: one piece varnished walnut http://www.icollector.com/Scarce-Early-Production-Black-Powder-Colt-Caliber-44-40-Single-Action-Army-Revolver_i10496448

For simplicity and durability, the really old black powder guns excel in longevity. I have a reproduction matchlock musket and cavalry pistol based on models from the 1590s. Fun to fire, but you're just happy the .75 and .69 caliber smoothbores can hit the paper, much less the target, beyond 40 yards.

- An old Chinese Hand Cannon on display at the Shaanxi history museum in Xi'An, China. The placard reads "Bronze firearm, Yuan dynasty (1271-1368 ACE)".

The medieval hand cannons from the 1300s were muzzle-loading guns attached to tillers (lengths of lumber like boat oars or just simple poles) and the gunner had to stuff a burning match or hot wire into the touch hole to fire it.
http://www.operatorchan.org/k/res/100476.html#100535- Tannenberg Handgonne pre-1399, Nuremberg Museum, Germany.

As for a durable modern firearm, I have heard of Glocks surviving 1000-round 15 minute torture tests, but I guess a Ruger Blackhawk or a Smith & Wesson Model 66 .357 Magnum would be difficult to beat for ruggedness and reliability in a modern (1970) pistol.
- US Smith & Wesson Model 66 2.5-inch .357 with a Tyler T-Grip.

The Smith & Wesson Model 27 is the original .357 Magnum revolver. It was first produced in 1935, and many versions of it are still in production today. The Model 27 was built on Smith & Wesson's carbon steel, large N-frame and is renowned for its durability and reliability.

The U.S. M6 Aicrew Survival rifle was a simple, robust, and compact combination gun designed to save pilots lives in the worst of conditions.
Learning from downed pilots during WWII, the U.S. Air Force sought out a simple survival rifle with which to equip their crews in rugged or hostile territory. A solution was provided by the Ithaca gun company in the form of a light, fold-able combination gun. This new rifle was evolved from earlier concepts like the “Marble Game Getter.” It was built to be rugged and weatherproof, made almost entirely of steel and a little plastic. Loaded by breaking open along the same hinge that folded it for storage, it was a single shot device. http://candrsenal.com/briefly-u-s-m6-aircrew-survival-rifle/

Two barrels, aligned vertically provided for chambering either a .410 shotgun shell or .22 hornet cartridge. The latter is a center-fire hunting round with a soft core and necessitated the inclusion of explicit instructions on the box that it not be used offensively or defensively to avoid a war crime. These two ammunition types provided amble ability to hunt a variety of small game or defend against medium sized predators. Nine .22 Hornet cartridges and four .410 shells can be stored inside a hatch in the butt of the M6.

The hammer was manually operated and had a selector on top to swap between .410 and .22. While the rear sight is not finely adjustable there are two positions provided, a shorter range leaf for the .410 and longer range aperture for the .22 Hornet. The trigger is a long squeeze bar on the underside and there is no safety mechanism. After firing, breaking the action open actuates an ejector to help empty the chambers.
Adopted in 1952, the M6 served into the 1970’s before being replaced. Because the M6 sports a 14” barrel it falls under Federal SBR laws, however Springfield has produced a civilian version with an 18” barrel, off and on, from the 1970’s.

Apart from the matchlock weapons I own, the most simple and sturdy firearm I have is a stainless Remington Derringer clone by the American Derringer Corp. of Waco, TX. in .45 Long Colt or .410 shotgun. Still has a few small part, but mostly this snake gun is built like a brick.

It's awesome on a single action 'cause you can let the recoil slip the gun up so the hammer's right there for re-cocking. I don't really think that's really super cool for anything that's not a single action revolver, but hey whatever floats your boat.

>>105708Some people love 'em, some hate 'em, and others think they're OK. You can put plenty of different grips on the old Peacemaker.
- US Colt SAA Bisley in .38 WCF restored by the Turnbull Manufacturing Company.